Storage, retrieval and sortation system

ABSTRACT

A material handling systems provides efficient storage, retrieval and sortation of articles, utilizing a plurality of carts capable of traveling under storage areas with a three dimensional warehouse system and on multiple levels. The carts may convey items from storage to a goods to operator user interface. The carts may function as decoupled sortation units capable of providing sortation at multiple mobile sortation locations, providing vertical sortation. Carts may include conveying surfaces, and sort articles from between carts. Carts may transport more than one article and a plurality of carts may transport a single article.

RELATED APPLICATION

This application claims priority from U.S. patent application Ser. No.13/843,168, filed on Mar. 15, 2013, that issued on 28 Apr. 2015 as nowU.S. Pat. No. 9,020,632, the disclosure of which is incorporated hereinby reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to material handling systems,and is more particularly directed to a system which provides efficientstorage, retrieval and sortation of articles. The innovation will bedisclosed in connection with, but not necessarily limited to, a threedimensional warehouse system utilizing a plurality of carts controlledto retrieve, store and sort containers or individual articles, capableof a wide range of uses, including a goods to operator system, asortation system and a storage and retrieval system.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate embodiments of the invention, and,together with the specification, including the detailed descriptionwhich follows, serve to explain the principles of the present invention.

FIG. 1 is a perspective illustration of a portion of a three dimensionalwarehouse system constructed in accordance with one or more teachings ofthe present invention.

FIG. 2 is a side view of a portion of the warehouse system illustratedin FIG. 1.

FIG. 3 is a top view of a portion of the warehouse system illustrated inFIG. 1.

FIG. 4 is a perspective illustration of a cart conveying a container.

FIG. 5 is a perspective illustration of the cart of FIG. 4.

FIG. 6 is a perspective illustration of an intersection of thenon-captive rail system of the warehouse system illustrated in FIG. 1.

FIG. 7 is a perspective illustration of two carts in a main aisle of thewarehouse system of FIG. 1.

FIG. 8 is a perspective illustration similar to FIG. 7 with surfaceshading to clarify components of the system.

FIG. 9 is a perspective illustration of a container in a storage area.

FIG. 10 is a perspective illustration of a cart partially disposed undera container in a storage area.

FIG. 11 is a perspective illustration of the cart elevator system of thewarehouse system of FIG. 1.

FIG. 12 is a perspective illustration of inclined ramps usable in thewarehouse system of FIG. 1.

FIG. 13 is a perspective illustration of a transfer station for removingor placing containers onto carts and into the warehouse system.

FIG. 14 is a perspective illustration of a system constructed inaccordance with one or more teachings of the present invention as agoods to operator system.

FIG. 15 is a perspective view of the system of FIG. 14 with the coverpanels of the operator interface omitted for clarity.

FIG. 16 is a front view of the system of FIG. 14 with the cover panelsof the operator interface omitted for clarity.

FIG. 17 is a perspective illustration of a portion of the system of FIG.14 showing containers at the operator interface and the lift.

FIG. 18 is a perspective illustration from the rear side of the sameportion of the system of FIG. 14 shown in FIG. 17.

FIG. 19 is a diagrammatic perspective illustration of a cart having alongitudinal lifting mechanism shown in an extended position.

FIG. 20 is a diagrammatic perspective illustration of a cart having atransverse lifting mechanism shown in an extended position.

FIG. 21 is a diagrammatic perspective illustration of a cart having alongitudinal lifting mechanism shown in an extended position and aconveyor.

FIG. 22 is a diagrammatic perspective illustration of a cart having atransverse lifting mechanism shown in an extended position and aconveyor.

FIG. 23 is a diagrammatic perspective illustration of a cart having aconveyor with rollers and belts extending longitudinally.

FIG. 24 is a diagrammatic perspective illustration of a cart having aconveyor with rollers and belts extending transversely.

FIG. 25 is a diagrammatic perspective illustration of a cart having alongitudinal lift mechanism shown in an extended position and aconveying surface defined by plurality of omni-directional drives.

FIG. 26 is a diagrammatic perspective illustration of a cart having atransverse lift mechanism shown in an extended position and a conveyingsurface defined by plurality of omni-directional drives.

FIG. 27 is a diagrammatic perspective illustration of a cart having aconveying surface defined by plurality of omni-directional drives.

FIG. 28 is a diagrammatic perspective illustration of cart having a“bomb bay” configuration.

FIG. 29 is diagrammatic perspective illustration of two carts withlongitudinally disposed conveying belts functioning in coordination witheach other to transfer an article therebetween.

FIG. 30 is diagrammatic perspective illustration of two carts withlongitudinally disposed conveying belts functioning in coordination witheach other to carry a single article.

FIG. 31 is a diagrammatic perspective illustration of two carts during avertical sort or transfer of an article from the upper cart to the lowercart directly below the upper cart.

FIG. 32 is a diagrammatic perspective illustration of two carts during avertical sort or transfer of an article from the upper cart to the lowercart which is located below and to the side of the upper cart.

FIG. 33 is a diagrammatic perspective illustration of a cart having aflipping flexible floor which may sort or discharge an article out thebottom.

Reference will now be made in detail to one or more embodimentsillustrated in the accompanying drawings.

DETAILED DESCRIPTION

In the following description, like reference characters designate likeor corresponding parts throughout the several views. Also, in thefollowing description, it is to be understood that terms such as front,back, inside, outside, and the like are words of convenience and are notto be construed as limiting terms. Terminology used in this patent isnot meant to be limiting insofar as devices described herein, orportions thereof, may be attached or utilized in other orientations.References herein to a x and y direction are only to provide referencedirections to aid in the description and are not to be construed asfeatures or aspects of the invention.

Referring to FIGS. 1-6, there is shown a three dimensional warehousesystem, generally indicated at 2, having frame 4 which defines a multilevel grid of paths and a plurality of mobile moveable platforms 6, alsoreferred to herein as carts or shuttles, which are controlled to movethroughout the grid. Frame 4 includes a plurality of spaced apart rails8 and 10 extending in the y direction see FIG. 2), which collectivelydefine a plurality of paths 12 along which carts 6 may travel. Frame 4also includes a plurality of spaced apart rails 14 and 16 extending inthe x direction see FIG. 2), which collectively define a plurality ofpaths 18 along which carts 6 may also travel. As described below, aplurality of x direction paths 18 a run under storage areas 20 wherecontainers 22, also referred to as totes, are stored. Warehouse system 2includes a plurality of container storage levels 24 a, 24 b, 24 c, andmay include a plurality of cart storage levels 26 a, 26 b, where cartsmay be stored during periods of low demand, or stored for charging, suchas by a contactless charger, or automated battery exchange. Elevator 28is configured to move carts 6 between the various levels, with orwithout containers. Thus, elevator 28 defines paths for carts 6 totravel long between locations on different levels. Although theembodiment illustrated is limited in size, with only three levels 24 a,24 b, 24 c, and only five rows of storage areas 20, warehouse system 2may have any suitable number of levels, storage areas and x and ydirection paths.

Warehouse system 2 includes controller 30 which executes softwareinstructions to implement the control logic which operates the system.Controller 30 may be programmed to control movements of carts 6, orcarts 6 may include a processing system which receives instructions fromcontroller 30 and executes software instructions to control its movementand operation. Carts 6 may locate themselves in any suitable way, suchas through a local positioning system, through location markers insystem 2, or distance and direction tracking. Controller 30 maycommunicate with carts 6 directly or indirectly, and with otherprocessing systems of warehouse system 2 in any suitable manner, such asby wireless communication, wired, or IR.

FIG. 6 illustrates an a typical intersection of tracks. Illustrated isintersection 32, of one of tracks 8 and one of tracks 14. As can beseen, the tracks are configured as a channel, sized and shaped toreceive and guide wheels carried of carts 6. Tracks 8, 10, 14, 16 may beof any suitable shape for supporting and guiding carts 6, such as a Lcross sectional shape. As seen in FIGS. 4, 5, 7 and 8, carts 6 include aplurality of wheels. Spaced apart wheels 34 a and 34 b are arrangedalong a first side of cart 6, configured to engage tracks 8. Spacedapart wheels 36 a and 36 b are arranged along a second side of cart 6opposite the first side, configured to engage tracks 10. Wheels 34 a, 34b, 36 a, 36 b comprise a first set which support cart 6 for movement inthe y direction. Similarly, spaced apart wheels 38 a and 38 b arearranged along a third side of cart 6, configured to engage tracks 14,and spaced apart wheels 40 a and 40 b are arranged along a fourth sideof cart 6 opposite the third side, configured to engage tracks 16.Wheels 38 a, 38 b, 40 a, 40 b comprise a second set which support cart 6for movement in the x direction.

Both the first and second wheel sets are selectively rotationally drivenclockwise or counterclockwise by a power source not seen) carried bycart 6 to advance cart 6 in the y direction or the x direction,respectively. Each wheel set is also selectively vertically moveable bythe cart power source. During movement in the y direction, the secondwheel set is in the up position so that the second wheel set does notengage either track 14 or 16. Similarly, during movement in the xdirection, the first wheel set is in the up position so that the firstwheel set does not engage either track 8 or 10. This allows cart 6 tomove in the desired direction past the intersections. When the directionof the cart is to be changed from the x direction to the y direction,the high wheel set is lowered and the low wheel set is raised, which canoccur simultaneously or sequentially. As will be appreciated, the changeindirection may be accomplished with only one wheel set being verticallymoveable provided that the lowest position of the vertically moveableset elevates the cart high enough that the other wheel set does notengage its tracks.

Referring to FIGS. 7-10, containers 22 may be stored in storage areas20. As seen in FIG. 9, storage area 20 includes spaced apart supports 42and 44, which engage container 22 at areas 46 and 48, leaving an openarea therebetween overlying the paths 18 a under storage areas 20sufficient to allow carts 6 to travel along the paths 18 a without beingimpeded by containers 22 or articles held or supported by storage areas20. To retrieve containers 22 in respective storage areas 20, emptycarts 6 travel along paths 18 a from a main aisle path 12 to a positionin storage area 20 underlying the container to be retrieved. FIG. 10illustrates cart 6 a moving into storage area 20 a to retrieve container22 a. Once under container 22 a, cart 6 a is out of the main aisle path12, leaving main aisle path 12 open for other carts 6 to travel alongwhile cart 6 a is retrieving or storing container 22 a. When cart 6 a isunder container 22 a, a lifting mechanism described below) of cart 6 awill raise, engage container 22 a and lift it out of engagement withsupports 42 and 44. Cart 6 a then moves along path 18 a to retrievecontainer 22 a, either in the opposite direction that it entered storagearea 20 a from, or if there is not a container in the storage areaadjacent storage area 20 a, continuing in the same direction carryingcontainer 22 a. If adjacent container 22 b is to be retrieved by cart 6a, cart 6 a could travel under and past container 22 a and stop belowcontainer 22 b, then retrieve it in the same described manner. Storing acontainer in storage areas 20 may be done in the reverse order, loweringcontainers 22 onto supports 42 and 44.

Although containers 22 are illustrated, individual articles not incontainers may also be stored in and retrieved from storage areas 20 inthe same way, with supports 46 and 48 configured complementary to thespecific physical characteristics of the article. The lifting mechanismsof carts 6 may have individually actuatable elements such that theeffective width or length of the lifting mechanism can be controlled tomatch the article. A large article may occupy a storage area larger thanthat occupied by a single container.

This configuration of warehouse system 2 also improves the efficiencyand response time in retrieving and storing containers or articles.FIGS. 7 and 8 illustrate carts 6 b and 6 c in the same main aisle path12. In the illustrated position, cart 6 c is impeding or movement ofblocking cart 6 b along path 12 the direction toward the top of FIG. 8.In such a case, cart 6 c may be directed to move from main aisle path12, into a storage area 20 along a path 18 a, until cart 6 b has passed.This avoids routing either cart 6 b or 6 c along less direct paths,providing improved efficiency and speed.

FIG. 11 illustrates elevator 28 which is configured to move carts 6between levels. Any suitable lifting/lowering mechanism may be used,such as the diagrammatically illustrated chain and sprocket arrangement50. A plurality of spaced apart supports 52 include tracks 54 configuredto receive a wheel set of carts 6. In the embodiment depicted, supports52 are sized to hold two carts 6, but any suitable size may be used.Elevator may be configured to convey carts 6 up or down, or an upelevator and down elevator may be provided. Elevator may be controlledin any suitable manner, such as locally by a dedicated elevatorcontroller.

FIG. 12 illustrates inclined paths 56, allowing carts 6 to change levelsunder their own power.

Introduction into or removal of containers or articles from system 2 maybe manual or automatic. FIG. 13 illustrates transfer station 58, bywhich containers or articles may be directed into or out of warehousesystem 2. One or more transfer stations may be located at any suitablelocation. Carts 6 d and 6 e are illustrated with spaced apart raisedlift elements 60. A plurality of conveyor elements 62 are illustrateddisposed with end portions 62 a aligned with and disposed in the spacesbetween lift elements 60 of cart 6 e. A container or article omitted forclarity) carried by cart 6 e would be engaged by conveyor elements 62 ascart 6 e advanced, with the container or article eventually beingtransferred to conveyor elements 62, as shown for container 22 c whichhas been transferred from cart 6 f. Container 22 c can thereafter bedirected to a downstream subsystem of the material handling system, suchto a merge, a sorter or directly to a loading bay. Carts 6 d, 6 e and 6f would then return to warehouse system 2 along a suitable path.Similarly, containers may be disposed onto carts with a reverse process.

Alternatively, carts 6 could be directed along paths to carry thecontainers or articles to their final destination, avoiding the need formerge and sortation systems. Carts would be routed back.

FIGS. 14-18 illustrate operator interface 64 of a goods to operatorsystem as part of warehouse system 2. Warehouse system 2, as describedabove, can dynamically introduce containers into and out of operatorinterface 64. Carts 6 transport containers 22 from storage areas 20 topick face 68 of operator interface 64. Containers 22 may remain on carts6, or be transferred by the lifting mechanisms of the cart onto supportsas described above, and as easily seen in FIGS. 15-18. Ether level,upper level 70 or lower level 72, may serve a pick function and theother level serve a put function, providing pick and put within the samestructure, in the same foot print. As described above, carts 6 are notlimited to a single level or plane of operation. Lift mechanism 74 isconfigured and controlled to move carts between upper level 70 and lowerlevel 72. As described above, the storage area which serves operatorinterface 64 may be of any size and number of levels. Articles fromother sources could even be added to containers 22 at operator interface64 and the containers returned to storages areas 20 within warehousesystem 2.

The upper surface of carts 6 may have any suitable configuration. It isnoted that different configurations may serve different functions, withthe different carts functioning together to achieve the desiredconveyance of containers and articles in an efficient manner. Swarmlogic might be applied to achieve such functionality.

FIGS. 19-30 illustrate various such upper surface configurations. Asdescribed above, carts 6 are configured to retrieve and store containers22 or articles in storage areas 20. Within the teachings herein, eachstorage area could include a respective lift mechanism for raising andlowering containers 22 or articles from or onto carts. However, carts 6are illustrated as including lift mechanisms. Referring to FIG. 19, liftelements 60 are diagrammatically illustrated in the raised, extendedposition. Lift elements 60 extend in a direction referred to herein aslongitudinal for ease of description only. Lift elements 60, as are anycart lifts or lift elements described herein, may be driven by the powersource carried by cart 6, being raised or lowered on command. Uppersurfaces 60 a of lift elements 60 may be configured as conveyingsurfaces capable of conveying containers or articles horizontally in thelongitudinal direction. As with the lift elements, any cart conveyingsurfaces or conveyors may be driven by the power source carried by thecart. Upper surfaces 60 a could be configured to remain above thesurrounding surface 6′ of cart 6, allowing the conveying surfaces tofunction when lift elements 60 are in the retracted, or lowered,position.

FIG. 20 diagrammatically illustrate lift elements 76 in the raised,extended position. Lift elements 76 extend in a direction referred toherein as transverse for ease of description only. Upper surfaces 76 aof lift elements 76 may be configured as conveying surfaces capable ofconveying containers or articles horizontally in the transversedirection. Upper surfaces 76 a could be configured to remain above thesurrounding surface 6′ of cart 6 g, allowing the conveying surfaces tofunction when lift elements 76 are in the retracted, or lowered,position.

FIG. 21 diagrammatically illustrate cart 6 h with longitudinal liftelements 78 in the raised, extended position. Interposed between liftelements 78 are conveying elements 80 illustrated as belt conveyors,extending in the longitudinal direction. When lift elements 78 areretracted, containers 22 or articles may engage and be conveyed byconveying elements 80. FIG. 22 is similar to FIG. 21, with cart 6 ihaving transverse lift elements 82 and transverse conveying elements 84,illustrated as belt conveyors.

FIG. 23 illustrates a plurality of spaced apart rollers 86 disposedlongitudinally on cart 6 j, configured to convey containers 22 orarticles in a transverse direction. A plurality of belt conveyors 88 areinterposed between rollers 86, also extending longitudinally butconfigured to convey containers 22 or articles in a longitudinaldirection. As will be appreciated, rollers 86 and belt conveyors 88 areconfigured similar to a right angle transfer conveyor. Belt conveyors 88are configured to be moved from a position below rollers 86 to aposition above rollers 86, as is necessary to disengage either beltconveyors 88 or rollers 86 from a container 22 or article in order to beable to convey such in the direction of the contacting conveyingelement. The raised position of belts may be configured to be highenough to lift containers 22 or articles from supports 42, 44.

FIG. 24 is similar to FIG. 23, with spaced apart rollers 90 disposedtransverse on cart 6 k, configured to convey containers 22 or articlesin a longitudinal direction. A plurality of belt conveyors 92 areinterposed between rollers 90, also extending transverse but configuredto convey containers 22 or articles in a transverse direction. Beltconveyors 92 function in the same manner as belt conveyors 88.

FIGS. 25, 26 and 27 have a plurality of omni-directional drives disposedin an array on surfaces 6′. Cart 6L has a plurality of lift longitudinallift elements 96. Cart 6 m has a plurality of transverse lift elements98. Cart 6 n does not have a lift element, and may serve to transportcontainers or articles deposited onto it, such as from other carts or byhand.

Cart 6 p of FIG. 28 is referred to as a “bomb bay” style cart, havingrecessed area 100 into which articles may be disposed, such as manuallyor from other carts. The bottom of recessed area 100 is formed by tworotatable doors 102, 104. Doors 102, 104 are selectively rotatable, uponcommand from controller 30 or an onboard processor of cart 6 p,discharging downwardly any article in recessed area 100. Thus, cart 6 pmay transfer articles to an underlying location, such as another cart ofany configuration, such as a bomb bay style cart, to an underlyingcontainer. Referring also to FIG. 31, cart 6 p″ is illustrated overlyingcart 6 p′, with door 102″ open. Article 112 is illustrated in theprocess of being vertically sorted to underlying cart 6 p′ at location114. Such transfer may occur in a predetermined location withinwarehouse system 2, such as at a designated transfer location that maybe configured with a guiding vertical chute, as diagrammaticallyindicated at 116, or an inclined chute, above a storage location holdingthe destination container. Such transfer may occur in non-fixedlocations, with controller 30 coordinating the paths and locations ofthe discharging cart and the receiving cart so as to effect thetransfer. Thus, cart 6 p is capable of serving a sort function, at fixedor mobile sort locations.

Similarly, carts having conveying elements of any configuration, suchillustrated in FIGS. 19-27, may serve, in addition to transportingitems, a sort function, also at fixed or mobile sort locations. Cartsmay be disposed adjacent each other on the same level, and the conveyingsurfaces operation coordinated to transfer containers or articles fromone cart to another. Carts 6 l, 6 m and 6 n may transfer articles in anydirection, provided other carts are appropriately located and operatedin coordination therewith.

Carts having conveying elements of any configuration, such illustratedin FIGS. 19-27, may also sort items vertically off of its side, to alower level receiving cart or container. Chutes or inclines may benecessary to ensure such articles reach the intended location. FIG. 32illustrates cart 6 r, having belt conveyor 118 disposed on its uppersurface. One level down and offset to a side, cart 6 s is disposed toreceive item 124, which is illustrated as having just slide off ofinclined chute 120, bounded at the ends by chute walls 122.

FIG. 33 is a diagrammatic perspective illustration of cart 6 t having aflipping flexible floor 126 which may sort or discharge an article outthe bottom of cart 6 t. Bottom 126 is depicted as flexible materialwhich may hang in a sling fashion or be tautly stretched between tworigid side members 128, 130. Ends of members 128, 130 engage conveyors132, 134. As conveyors 132, 134 advance in the same direction, bottom126 will flip over and any article will fall out the bottom to anunderlying cart not shown.

FIG. 29 illustrates carts 6 q illustrate article 106 being transferredfrom one cart to the other by longitudinal conveyor belt 108.

FIG. 30 illustrates two carts 6 r functioning together to carry a singlearticle 110, depicted as a couch. In warehouse system 2, two or morecarts 6 may be directed to function together to move a single article.Movement of carts 6 r must be coordinated, and the paths traveledcapable of accommodating turns with an article spanning a plurality ofcarts. Carts 6 r could be configured with a driven or freely rotatablesurface supporting and engaging article 110 to accommodate the necessaryrelative rotational motion between article 110 and carts 6 r duringturns.

In accordance with various aspects of the disclosure, an element, or anyportion of an element, or any combination of elements may be implementedwith a “processing system” that includes one or more physical devicescomprising processors. Non-limiting examples of processors includemicroprocessors, microcontrollers, digital signal processors DSPs),field programmable gate arrays FPGAs), programmable logic devices PLDs),programmable logic controllers PLCs), state machines, gated logic,discrete hardware circuits, and other suitable hardware configured toperform the various functionality described throughout this disclosure.One or more processors in the processing system may executeinstructions. A processing system that executions instructions to effecta result is a processing system which is configured to perform taskscausing the result, such as by providing instructions to one or morecomponents of the processing system which would cause those componentsto perform acts which, either on their own or in combination with otheracts performed by other components of the processing system would causethe result. Software shall be construed broadly to mean instructions,instruction sets, code, code segments, program code, programs,subprograms, software modules, applications, software applications,software packages, routines, subroutines, objects, executables, threadsof execution, procedures, functions, etc., whether referred to assoftware, firmware, middleware, microcode, hardware descriptionlanguage, or otherwise. The software may reside on a computer-readablemedium. The computer-readable medium may be a non-transitorycomputer-readable medium. Computer-readable medium includes, by way ofexample, a magnetic storage device e.g., hard disk, floppy disk,magnetic strip), an optical disk e.g., compact disk CD), digitalversatile disk DVD)), a smart card, a flash memory device e.g., card,stick, key drive), random access memory RAM), read only memory ROM),programmable ROM PROM), erasable PROM EPROM), electrically erasable PROMEEPROM), a register, a removable disk, and any other suitable medium forstoring software and/or instructions that may be accessed and read by acomputer. The computer-readable medium may be resident in the processingsystem, external to the processing system, or distributed acrossmultiple entities including the processing system. The computer-readablemedium may be embodied in a computer-program product. By way of example,a computer-program product may include a computer-readable medium inpackaging materials. Those skilled in the art will recognize how best toimplement the described functionality presented throughout thisdisclosure depending on the particular application and the overalldesign constraints imposed on the overall system.

EXPLICIT DEFINITIONS

“Processor” means devices which can be configured to perform the variousfunctionality set forth in this disclosure, either individually or incombination with other devices. Examples of “processors” includemicroprocessors, microcontrollers, digital signal processors DSPs),field programmable gate arrays FPGAs), programmable logic devices PLDs),programmable logic controllers PLCs), state machines, gated logic, anddiscrete hardware circuits. The phrase “processing system” is used torefer to one or more processors, which may be included in a singledevice, or distributed among multiple physical devices.

“Instructions” means data which can be used to specify physical orlogical operations which can be performed by a processor. Instructionsshould be interpreted broadly to include, code, code segments, programcode, programs, subprograms, software modules, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, hardwaredescription language, middleware, etc., whether encoded in software,firmware, hardware, microcode, or otherwise.

A statement that a processing system is “configured” to perform one ormore acts means that the processing system includes data which mayinclude instructions) which can be used in performing the specific actsthe processing system is “configured” to do. For example, in the case ofa computer a type of “processing system”) installing Microsoft WORD on acomputer “configures” that computer to function as a word processor,which it does using the instructions for Microsoft WORD in combinationwith other inputs, such as an operating system, and various peripheralse.g., a keyboard, monitor, etc. . . . ).

The foregoing description has been presented for purposes ofillustration and description. It is not intended to be exhaustive or tolimit the invention to the precise form disclosed. Obvious modificationsor variations are possible in light of the above teachings. Theembodiment was chosen and described in order to illustrate theprinciples of the invention and its application to thereby enable one ofordinary skill in the art to utilize the invention in variousembodiments and with various modifications as are suited to theparticular use contemplated. Although only a limited number ofembodiments of the invention is explained in detail, it is to beunderstood that the invention is not limited in its scope to the detailsof construction and arrangement of components set forth in the precedingdescription or illustrated in the drawings. The invention is capable ofother embodiments and of being practiced or carried out in various ways.Also, specific terminology was used herein for the sake of clarity. Itis to be understood that each specific term includes all technicalequivalents which operate in a similar manner to accomplish a similarpurpose. It is intended that the scope of the invention be defined bythe claims submitted herewith.

The invention claimed is:
 1. A material handling system for storing andretrieving containers or articles, comprising: a grid comprising a firstplurality of first paths defined by a plurality of spaced apart tracksextending in a first direction; and a second plurality of second pathsdefined by a plurality of spaced apart tracks extending in a seconddirection that is orthogonal to the first plurality of first paths; aplurality of carts having a first set of wheels configured toselectively travel along said first paths and having a second set ofwheels configured to selectively travel along said second paths; aplurality of storage areas, respective portions of a third plurality ofsaid second paths underlying said storage areas, said storage areasconfigured to support containers or articles above said respectiveunderlying portions such that said carts may travel along saidunderlying portions without being impeded by containers or articles heldby said storage areas; and a controller in communication with saidplurality of carts, wherein said controller comprises at least oneprocessor that executes instructions to cause said carts to performoperations, said operations comprising selectively traveling to any of aplurality of locations within said grid, said travel including travelingalong respective underlying portions of said second paths to reachdestinations not on said respective underlying portions.
 2. The materialhandling system of claim 1, wherein a first plurality of said pluralityof carts is configured with a lift configured to engage containers orarticles held within said storage area such that said carts may removesuch engaged containers or articles from said storage area.
 3. Thematerial handling system of claim 1, wherein a plurality of saidplurality of carts comprises respective conveying surfaces.
 4. Thematerial handling system of claim 1, wherein said grid comprises aplurality of levels, and said instructions cause a plurality of saidcarts to travel to locations on more than one level.
 5. The materialhandling system of claim 4, wherein said grid comprises at least onethird path leading between said levels, and wherein said instructionscause said carts to travel along said third paths when traveling betweenlocations on different levels.
 6. The material handling system of claim5, wherein said at least one third path comprises an elevator.
 7. Thematerial handling system of claim 5, wherein said at least one thirdpath comprises an inclined path.
 8. A material handling system fortransporting articles, comprising: a first path and a second path, aportion of said first path overlying a portion of said second path at afirst location; at least one first cart configured to travel along saidfirst path; at least one second cart configured to travel along saidsecond path; and a controller in communication with at least said atleast one first cart, wherein said controller comprises at least oneprocessor that executes instructions to cause said at least one firstcart to perform operations, said operations comprising discharging anarticle carried by said first cart onto said second cart when said firstand second carts are proximal said first location.
 9. The materialhandling conveyor of claim 8, wherein said at least one first cartcomprises an upper conveying surface, and said article is discharged offof a side of said at least one first cart.
 10. The material handlingconveyor of claim 8, wherein said at least one first cart comprises abottom which moveable to a position at which said cart has an openbottom such that said article is discharged through said open bottom.11. A material handling system for transporting containers or articles,comprising: a first path; a first cart configured to travel along saidfirst path, said first cart comprising an upper conveying surface; asecond cart configured to travel along said first path, said second cartcomprising an upper conveying surface; and a controller in communicationwith at least said first cart, wherein said controller comprises atleast one processor that executes instructions to cause said first cartto perform operations, said operations comprising discharging acontainer or article carried by said first cart as least partially ontosaid second cart when said first and second carts are proximal eachother.
 12. The material handling system of claim 11, wherein saidoperations further comprise said first and second carts traveling inunison to transport the article positioned on both said first and secondcarts.
 13. A controller for controlling a material handling systemcomprising a grid comprising a first plurality of first paths defined bya plurality of spaced apart tracks extending in a first direction; and asecond plurality of second paths defined by a plurality of spaced aparttracks extending in a second direction; a plurality of carts having afirst set of wheels configured to selectively travel along said firstpaths and having a second set of wheels configured to selectively travelalong said second paths; and a plurality of storage areas, respectiveportions of a third plurality of said second paths underlying saidstorage areas, said storage areas configured to support containers orarticles above said respective underlying portions such that said cartsmay travel along said underlying portions without being impeded bycontainers or articles held by said storage areas; wherein said whereinthe controller comprises at least one processor that executesinstructions to cause said carts to perform operations, said operationscomprising selectively traveling to any of a plurality of locationswithin said grid, said traveling including traveling along respectiveunderlying portions of said second paths to reach destinations not onsaid respective underlying portions.
 14. The controller of claim 13,wherein said operations comprise causing said first one of said carts toreturn to said first path after said second one of said carts haspassed.
 15. A controller for controlling a material handling systemcomprising a first path, a first cart configured to travel along saidfirst path, said first cart comprising an upper conveying surface, asecond cart configured to travel along said first path, said second cartcomprising an upper conveying surface, the controller comprises at leastone processor that executes instructions to cause said first cart toperform operations, said operations comprising discharging a containeror article carried by said first cart at least partially onto saidsecond cart when said first and second carts are proximal each other.16. The controller of claim 15, wherein said operations further comprisesaid first and second carts traveling in unison to transport the articlepositioned on both said first and second carts.
 17. A material handlingsystem for storing and retrieving containers or articles, comprising: agrid comprising a first plurality of first paths defined by a pluralityof spaced apart tracks extending in a first direction; and a secondplurality of second paths defined by a plurality of spaced apart racksextending in a second direction; a plurality of carts configured toselectively travel along said first and second paths, wherein at leastone first cart comprises a bottom which moveable to a position at whichsaid cart has a selectably open bottom such that an article isselectively discharged through said open bottom; a plurality of storageareas, respective portions of a third plurality of said second pathsunderlying said storage areas, said storage areas configured to supportcontainers or articles above said respective underlying portions suchthat said carts may travel along said underlying portions without beingimpeded by containers or articles held by said storage areas; and acontroller in communication with said plurality of carts, wherein saidcontroller comprises at least one processor that executes instructionsto cause said carts to perform operations, said operations comprisingselectively traveling to any of a plurality of locations within saidgrid, said travel including traveling along respective underlyingportions to discharge said article into a container.
 18. A controllerfor a material handling system for storing and retrieving containers orarticles comprising a grid comprising a first plurality of first pathsdefined by a plurality of spaced apart tracks extending in a firstdirection and a second plurality of second paths defined by a pluralityof spaced apart tracks extending in a second direction; a plurality ofcarts configured to selectively travel along said first and secondpaths, wherein at least one first cart comprises a bottom which moveableto a position at which said cart has a selectably open bottom such thatan article is selectively discharged through said open bottom; aplurality of storage areas, respective portions of a third plurality ofsaid second paths underlying said storage areas, said storage areasconfigured to support containers or articles above said respectiveunderlying portions such that said carts may travel along saidunderlying portions without being impeded by containers or articles heldby said storage areas the controller in communication with saidplurality of carts, wherein said controller comprises at least oneprocessor that executes instructions to cause said carts to performoperations, said operations comprising selectively traveling to any of aplurality of locations within said grid, said travel including travelingalong respective underlying portions to discharge said article into acontainer.